1. Field of the Invention
This invention relates to thermal printers and more particularly to a system and method for increasing the operational life of a thermal printhead in a thermal printer by selectively changing, from document to document or print line to print line, the absolute position of the characters to be printed by associated elements in the printhead.
2. Description of the Prior Art
Different types of thermal printer systems have been proposed for improving the operational capabilities of thermal printers by shifting the position of the print line under certain operational conditions.
U.S. Pat. No. 4,453,166 discloses a method and device for avoiding a detected defective element in a thermal printer by shifting the printing data one to three bits in either direction so that a non-printing bit in the printing data is positioned at the position of the defective element to enable the thermal printing operation to be continued.
The above-referenced U.S. patent application Ser. No. 640,894 discloses a system and method for automatically detecting defective thermal printhead elements in a thermal printer and for automatically correcting for at least one defective thermal printhead element by shifting the entire serial print line such that the defective element is assigned to a position between adjacent characters that are to be printed.
None of the above-cited thermal printers increases the useful life of a thermal printhead by automatically selectively shifting, from document to document, the entire print line of characters to be printed in order to achieve a more balanced use of the elements in the thermal printhead.